Many ores mined throughout the world contain economically significant concentrations of certain mineral values such as gold, silver, platinum, gallium, germanium, indium and the like. These mineral values may be present in an uncombined form or in combination with various other components of the ore such as coal. Many ores contain as little as 2% coal, the coal, however, containing high concentrations of the desired mineral values.
Standard methods of concentrating these coal fractions from ore, e.g. flotation, have not proven to be effective. Because the coal fraction of interest is usually dispersed throughout the mineral matrix of the ore, the coal is usually oxidized, and therefore conventional collectors such as fuel oil are ineffective. Other methods of concentration such as spirals or jigs have also failed to achieve satisfactory separations of the carbonaceous fraction.
The use of various acidic collectors for coal flotation are disclosed in published EPO Applications Nos. 0,106,787 (4/25/84) and 84/109310/18 while U.S. Pat. Nos. 4,253,944; 4,278,533; 4,305,815; 4,330,339 disclose acid reaction products for the same purpose. The materials are either expensive or difficult to produce and therefore a search for new, effective collectors continues.
Therefore, if a process could be devised whereby the coal, particularly if oxidized, is recoverable economically and effectively as a mineral value bearing fraction, from ore, a significant step forward in the art would be realized.